One possible analysis could be that it allows for a more personalized take on the 'Owari no Seraph' universe. OC (original character) fanfictions often bring in new storylines and character dynamics. It might explore relationships between the existing characters in the series and the newly created OC in unique ways, such as a romantic relationship or a friendship that changes the course of the story.
The theme of identity is quite prevalent in such fanfictions. The OC has to figure out who they are in this new and often dangerous world of 'Owari no Seraph'. Are they going to be a hero, a villain, or something in between? Another theme that can't be ignored is survival. The world of 'Owari no Seraph' is full of threats, and the OC has to find ways to survive. This can lead to some really exciting adventure - like storylines where the OC has to use their wits and any special abilities they might have.
One common theme is survival. Given the post - apocalyptic setting of 'Owari no Seraph', many oc fanfictions focus on how the original characters endure and fight for their lives. Another theme is friendship. The oc often forms strong bonds with the existing characters, like Yuuichiro and Mikaela. For example, in some fanfictions, the oc and Yuuichiro help each other in battles and grow to trust each other deeply.
I think 'The Mysterious Oc' is a great 'owari no seraph oc fanfiction'. This fic creates an oc with a mysterious origin that gradually unfolds throughout the story. The oc's interactions with the known characters are well - written. Also, 'The Oc's Alliance' is worth reading. In it, the oc forms an unexpected alliance and together they face the challenges in the 'Owari no Seraph' universe. It has a lot of action and interesting character dynamics.
One popular theme is the exploration of their friendship in extreme situations. How they support each other when facing powerful enemies in the Owari no Seraph universe.
Another theme is friendship. OCs often form strong bonds with the existing characters. For example, they might team up with Yuuichiro and the others to fight against the common enemy. This theme helps to integrate the OC into the story world.
The main characters are Krul and Mika. Krul is a vampire, and she has a significant role in the 'owari no seraph' series. She is often depicted as a powerful and somewhat mysterious figure. Mika, on the other hand, is also an important character. He has his own set of abilities and a complex backstory that often gets intertwined with Krul's in fanfiction.
Another theme could be sacrifice. Guren and Sayuri might be put in situations where they have to sacrifice something for the other, whether it's their own safety, their reputation, or something else. This can add a lot of emotional depth to the stories. In many fanfictions, there's also the theme of redemption. Maybe one of them has made mistakes in the past and the other helps them find a way to redeem themselves through their relationship.
In fanfiction, Yuu's character might be developed by showing his vulnerability more when it comes to Shinoa. For example, he could be more open about his fears and insecurities around her. Shinoa, on the other hand, could be developed by showing her softer side towards Yuu. She might let down her tough - girl facade and be more affectionate.
One popular theme could be the complex relationship between Krul and Mika. Maybe exploring how their different natures interact, like Krul being a vampire and Mika having his own unique situation. Another theme might be their shared experiences in the 'owari no seraph' world, such as facing common enemies or dealing with the power dynamics within their groups.